US7558089B2ExpiredUtilityPatentIndex 80
Method and apparatus for space vector modulation in multi-level inverters
Assignee: ADVANCED ENERGY CONVERSION LLCPriority: Dec 13, 2005Filed: Dec 13, 2006Granted: Jul 7, 2009
Est. expiryDec 13, 2025(expired)· nominal 20-yr term from priority
H02M 7/53876H02M 7/487
80
PatentIndex Score
15
Cited by
20
References
8
Claims
Abstract
An apparatus for space vector modulation of a multi-level inverter, the apparatus comprising: a triangle generator for finding a modulation triangle enclosing a reference voltage vector, the modulation triangle comprising vertex vectors; a duty ratio calculator for determining duty ratios for the vertex vectors; a switching function selector for selecting switching functions corresponding to the vertex vectors; a forbidden transition identifier for identifying a forbidden transition between two of the vertex vectors; and a control module for applying the switching functions to the multi-level inverter according to the duty ratios and avoiding the forbidden transition.
Claims
exact text as granted — not AI-modified1. An apparatus for space vector modulation of a multi-level inverter, said apparatus comprising:
a triangle generator for finding a modulation triangle enclosing a reference voltage vector, said modulation triangle comprising vertex vectors;
a duty ratio calculator for determining duty ratios for said vertex vectors;
a forbidden transition identifier for identifying a forbidden transition between two of said vertex vectors;
a control module for applying said switching functions to said multi-level inverter according to said duty ratios and avoiding said forbidden transition; and
a switching function selector for selecting switching functions corresponding to said vertex vectors, wherein said switching function selector comprises:
a vertex level computer for computing vertex levels corresponding to said vertex vectors, each of said vertex vectors being described by a respective skew coordinate pair, (G, H), each of said vertex levels, L, being computed according to the rule:
L
=
{
abs
(
H
)
,
if
G
=
0
or
G
+
H
=
0
abs
(
G
)
,
if
H
=
0
H
sin
(
2
π
/
3
)
/
sin
(
T
)
,
otherwise
where
T
=
tan
-
1
(
H
sin
(
2
π
/
3
)
G
+
H
cos
(
π
/
3
)
)
and “abs( )” denotes the absolute value function:
a triangle level computer for computing a triangle level, K, equal to the maximum of said vertex levels;
a switching function computer for computing said switching functions, each of said switching functions, V, being computed according to the rule:
V
=
{
[
K
,
abs
(
K
-
abs
(
G
)
)
,
abs
(
K
-
abs
(
G
)
-
abs
(
H
)
)
]
,
if
G
>
0
and
(
G
+
H
)
>
0
[
abs
(
K
-
abs
(
G
)
)
,
K
,
abs
(
K
-
abs
(
H
)
)
]
,
if
G
<
0
and
H
>
0
[
abs
(
K
-
abs
(
G
)
-
abs
(
H
)
)
,
abs
(
K
-
abs
(
H
)
)
,
K
]
,
if
H
<
0
and
(
G
+
H
)
<
0
.
2. The apparatus of claim 1 wherein said forbidden transition identifier comprises:
a forbidden transition module for identifying as forbidden a transition between a first vertex vector, having skew coordinates (G 1 ,H 1 ), and a second vertex vector, having skew coordinates (G 2 ,H 2 ) if
( G 1 >0 and G 1 +H 1 >0 and G 2 >0 and G 2 +H 2 >0 and H 1 −H 2 =0)
or
( G 1 <0 and H 1 >0 and G 2 <0 and H 2 >0 and G 1 −G 2 +H 1 −H 2 =0)
or
( H 1 <0 and G 1 +H 1 <0 and H 2 <0 and G 2 +H 2 <0 and G 1 −G 2 =0).
3. The apparatus of claim 1 wherein said control module is configured for performing the acts of:
denoting said switching functions respectively as V 1 , V 2 , V 3 , said forbidden transition being between V 1 and V 3 ; and
repeating said switching functions in the order V 1 , V 2 , V 3 , V 3 , V 2 , V 1 .
4. An apparatus for space vector modulation of a multi-level inverter system, said apparatus comprising:
a triangle generator for finding a modulation triangle enclosing a reference voltage vector, said modulation triangle comprising vertex vectors;
a duty ratio calculator for determining duty ratios for said vertex vectors;
a switching function selector for selecting switching functions corresponding to said vertex vectors;
a forbidden transition identifier for identifying a forbidden transition between two of said vertex vectors; and
a control module for applying said switching functions to said multi-level inverter according to said duty ratios and avoiding said forbidden transition,
said switching function selector comprising:
a vertex level computer for computing vertex levels corresponding to said vertex vectors, each of said vertex vectors being described by a respective skew coordinate pair, (G, H), each of said vertex levels, L, being computed according to the rule:
L
=
{
abs
(
H
)
,
if
G
=
0
or
G
+
H
=
0
abs
(
G
)
,
if
H
=
0
H
sin
(
2
π
/
3
)
/
sin
(
T
)
,
otherwise
where
T
=
tan
-
1
(
H
sin
(
2
π
/
3
)
G
+
H
cos
(
π
/
3
)
)
and “abs( )” denotes the absolute value function;
a triangle level computer for computing a triangle level, K, equal to the maximum of said vertex levels;
a switching function computer for computing said switching functions, each of said switching functions, V, being computed according to the rule:
V
=
{
[
K
,
abs
(
K
-
abs
(
G
)
,
abs
(
K
-
abs
(
G
)
-
abs
(
H
)
)
]
,
if
G
>
0
and
(
G
+
H
)
>
0
[
abs
(
K
-
abs
(
G
)
)
,
K
,
abs
(
K
-
abs
(
H
)
)
]
,
if
G
<
0
and
H
>
0
[
abs
(
K
-
abs
(
G
)
-
abs
(
H
)
)
,
abs
(
K
-
abs
(
H
)
)
,
K
]
,
if
H
<
0
and
(
G
+
H
)
<
0
said forbidden transition identifier comprising:
a forbidden transition module for identifying as forbidden a transition between a first vertex vector, having skew coordinates (G 1 ,H 1 ), and a second vertex vector, having skew coordinates (G 2 ,H 2 ) if
( G 1 >0 and G 1 +H 1 >0 and G 2 >0 and G 2 +H 2 >0 and H 1 −H 2 =0)
or
( G 1 <0 and H 1 >0 and G 2 <0 and H 2 >0 and G 1 −G 2 +H 1 −H 2 =0)
or
( H 1 <0 and G 1 +H 1 <0 and H 2 <0 and G 2 +H 2 <0 and G 1 −G 2 =0).
5. The apparatus of claim 4 wherein said control module is configured for performing the acts of:
denoting said switching functions respectively as V 1 , V 2 , V 3 , said forbidden transition being between V 1 and V 3 ; and
repeating said switching functions in the order V 1 , V 2 , V 3 , V 3 , V 2 , V 1 .
6. A method of space vector modulation for a multi-level inverter system, said method comprising the acts of:
finding a modulation triangle enclosing a reference voltage vector, said modulation triangle comprising vertex vectors;
determining duty ratios for said vertex vectors;
selecting switching functions corresponding to said vertex vectors;
identifying a forbidden transition between two of said vertex vectors;
applying said switching functions to said multi-level inverter according to said duty ratios and avoiding said forbidden transition; and
selecting switching functions corresponding to said vertex vectors, such act comprising:
computing vertex levels corresponding to said vertex vectors, each of said vertex vectors being described by a respective skew coordinate pair, (G, H), each of said vertex levels, L, being computed according to the rule:
L
=
{
abs
(
H
)
,
if
G
=
0
or
G
+
H
=
0
abs
(
G
)
,
if
H
=
0
H
sin
(
2
π
/
3
)
/
sin
(
T
)
,
otherwise
where
T
=
tan
-
1
(
H
sin
(
2
π
/
3
)
G
+
H
cos
(
π
/
3
)
)
and “abs( )” denotes the absolute value function;
computing a triangle level, K, equal to the maximum of said vertex levels;
computing said switching functions, each of said switching functions, V, being computed according to the rule:
V
=
{
[
K
,
abs
(
K
-
abs
(
G
)
)
,
abs
(
K
-
abs
(
G
)
-
abs
(
H
)
)
]
,
if
G
>
0
and
(
G
+
H
)
>
0
[
abs
(
K
-
abs
(
G
)
)
,
K
,
abs
(
K
-
abs
(
H
)
)
]
,
if
G
<
0
and
H
>
0
[
abs
(
K
-
abs
(
G
)
-
abs
(
H
)
)
,
abs
(
K
-
abs
(
H
)
)
,
K
]
,
if
H
<
0
and
(
G
+
H
)
<
0
.
7. The method of claim 6 wherein said act of identifying a forbidden transition between two of said vertex vectors comprises:
identifying as forbidden a transition between a first vertex vector, having skew coordinates (G 1 ,H 1 ), and a second vertex vector, having skew coordinates (G 2 ,H 2 ) if
( G 1 >0 and G 1 +H 1 >0 and G 2 >0 and G 2 +H 2 >0 and H 1 −H 2 =0)
or
( G 1 <0 and H 1 >0 and G 2 <0 and H 2 >0 and G 1 −G 2 +H 1 −H 2 =0)
or
( H 1 <0 and G 1 +H 1 <0 and H 2 <0 and G 2 +H 2 <0 and G 1 −G 2 =0).
8. The method of claim 6 wherein said act of applying said switching functions to said multi-level inverter comprises:
denoting said switching functions respectively as V 1 , V 2 , V 3 , said forbidden transition being between V 1 and V 3 ; and
repeating said switching functions in the order V 1 , V 2 , V 3 , V 3 , V 2 , V 1 .Cited by (0)
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